1. Field of the Invention
Apparatuses consistent with the present invention relate to electronic devices such as portable telephones, portable personal computers, and the like, in which a plurality of enclosures having circuits are installed so as to enable relative displacement, and the circuits within these enclosures are electrically connected by means of micro-coaxial cables or other wiring, as well as to a harness for use in wiring between enclosures of such electronic devices.
2. Description of the Related Art
In recent years, electronic devices such as portable telephones have made rapid advances toward compactness, lighter weight, and greater functionality. Current technical trends include an increased demand for micro-coaxial cable assemblies in place of flexible printed circuit boards (hereafter referred to as “FPCs”) as internal wiring members of portable telephones. This is due to the fact that the transmission characteristics and noise resistance of micro-coaxial cables is well-suited to marked demands. Further, wiring methods are being sought which enable use even in mechanical constructions which had previously been regarded as ill-suited to micro-coaxial cables.
Conventional micro-coaxial cable assemblies have been adopted in place of FPCs as internal wiring members of portable telephones. The mechanical construction of portable telephones in which micro-coaxial cable assemblies are used include the open-close construction called a “clamshell” type device as shown in FIG. 13A; the rotating construction called a “jackknife” type device as shown in FIG. 13B; and a dual-axis construction enabling both rotation and opening/closing called a “twist” type device as shown in FIG. 13C. However, there has been no use of micro-coaxial cable assemblies in a parallel-displacement construction called a “sliding” type device such as shown in FIG. 13D.
Characteristics sought in a sliding-type construction include horizontal flexing in a space 3 mm in height. In the related art, only FPCs, with a thin-sheet construction, have been compatible with such a construction. FIG. 14 illustrates an example of a case of application of an FPC 4 as a member for wiring between enclosures of a sliding-type electronic device 1. In this electronic device 1, the circuits of a first enclosure 2, and of a second enclosure 3 slidably mounted on the first enclosure 2, are electrically connected by the FPC 4.
Examples of technology related to multi-core cables used in micro-coaxial cable assemblies and the like are disclosed in Japanese Unexamined Patent Applications, First Publication Nos. 2005-235690 and 2005-141923.
Japanese Unexamined Patent Application, First Publication No. 2005-235690, discloses a multi-core cable wherein both end portions of a plurality of conductors are arranged in a flat shape with a prescribed pitch, and the central portion is bundled into a single cable.
Japanese Unexamined Patent Application, First Publication No. 2005-141923, discloses a multi-core cable wherein a weft is woven among a plurality of conductors, and by means of contraction of the weft, the conductors are bundled into an approximately round shape.
However, the above technologies of the related art have the following problems.
As shown in FIG. 14, in a sliding-type electronic device employing FPCs as wiring members between enclosures, transmission characteristics and noise resistance are inadequate. Further, because the FPC is flexed in a small space, there is the possibility that creases and bending may occur in the FPC, which may worsen the transmission characteristics.
As previously explained, if a micro-coaxial cable is used as a wiring member between enclosures in a sliding-type electronic device, transmission characteristics and noise resistance may be improved compared with cases in which FPCs are used as wiring members. However, the harness constructions of the related art disclosed in Japanese Unexamined Patent Application, First Publication No. 2005-235690 and No. 2005-141923 are used in clamshell-type and jackknife-type constructions, and cannot be applied to sliding-type constructions. The harness constructions of the related art are constructions in which a plurality of cables are bundled, and so the 3 mm height of flexing space required by sliding-type constructions cannot be maintained.
FIG. 15 is a reference diagram showing the wiring structure in a sliding-type electronic device of the related art. Sliding-type electronic device 5 comprises a first enclosure 6 having a first connection portion 8, and a second enclosure 7 slidably mounted on the first enclosure 6 having a second connection portion 9. In sliding-type electronic device 5, each connection portion is provided such that the wires connecting the first connection portion 8 and second connection portion 9 are parallel to the direction of enclosure displacement 10 (the enclosure sliding direction). When a harness (not shown) is used as the wiring member between enclosures, wiring is performed at the harness wiring position indicated by the symbol 10A.
In general, micro-coaxial cables used in portable telephones range from American Wire Gauge (AWG) 46 to AWG 42 where the cable external diameter is approximately 0.2 mm to 0.3 mm. The flexing spaces used in sliding-type constructions generally have a height of approximately 3 mm, so that flexing resistance of approximately 100,000 cycles or more is required.
In general, the allowable bending radius of micro-coaxial cables must be a bending radius equal to approximately 20 times the conductor diameter. When the cable diameter is approximately 0.2 mm to 0.3 mm, and is for example 0.25 mm, an allowable bending radius of approximately 5 mm is required. Thus, the 3 mm flexing space required for general sliding-type constructions would not be not satisfied.
Further, related art harnesses disclosed in Japanese Unexamined Patent Application, First Publication No. 2005-235690 and in Japanese Unexamined Patent Application, First Publication No. 2005-141923, numerous cables are bundled together, and these are connected at the wiring position indicated by the symbol 10A in FIG. 15. When the enclosure 7 is slid, flexing results in the space of a height of 3 mm so that the cable is creased and flexing resistance performance is further decreased.
Maintaining the required flat shape of the harness cables presents other problems. For example, when a harness configured without a bundling member is flexed, the flat shape cannot be preserved due to cable creasing and stretching.